2 Boardworks A2 Biology Genetic Technologies Teacher notesIn ‘Slide Show’ mode, click the name of a section to jump straight to that slide.
3 Boardworks A2 Biology Genetic Technologies What is cloning?Boardworks A2 BiologyGenetic TechnologiesCloning is the production of identical copies of organisms, cells or DNA.A clone is a genetically identical organism or a group of genetically identical cells derived from a single parent.Cloning occurs in nature as part of growth and reproduction. This natural process can be manipulated to produce clones of organisms artificially.Photo credit: Jerome Wexler / Science Photo LibraryTeacher notesStrawberry plants use vegetative propagation to produce new plants, which are clones. The plants have adapted specialized stems or runners that grow along the ground from the parent plant. The cells in the tip of the runner can then divide and differentiate forming the roots and shoots of the new strawberry plant.
12 Disadvantages of reproductive cloning Boardworks A2 BiologyGenetic TechnologiesThe first cloned mammal, Dolly the sheep, died prematurely due to lung disease. This raised concerns about the health and life expectancy of cloned animals.It is thought that some cloned mammals will have shorter telomeres than other animals of the same again. Telomeres are pieces of non-coding DNA that prevent the chromosome from degrading. They shorten as cells divide and are therefore considered a measure of ageing in cells.Photo credit: PH. Plailly / Eurelios / Science Photo Library
14 Boardworks A2 Biology Genetic Technologies Adult stem cellsBoardworks A2 BiologyGenetic TechnologiesIn mature animals only a few stem cells remain. These are multipotent. They have the capacity to differentiate into only a few specific cell types. They maintain and repair specific tissues in the body.Adult stem cells do not provide the same flexibility as embryonic stem cells. However, adult stem cells can be used to produce a limited range of tissues for transplantation.Teacher notesSee the Boardworks AS Biology ‘Cell Division’ presentation for more information about stem cells.For example, adult haematopoietic stem cells from bone marrow have been used in transplants for 40 years. These stem cells form all the blood cell types in the body.
15 Take a vote: therapeutic cloning Boardworks A2 BiologyGenetic Technologies
16 Boardworks A2 Biology Genetic Technologies Teacher notesIn ‘Slide Show’ mode, click the name of a section to jump straight to that slide.
17 How is genetic engineering useful? Boardworks A2 BiologyGenetic TechnologiesGenetic engineering involves inserting a foreign gene into an organism’s genome, resulting in the expression of the new gene.This method can be used to engineer recombinant organisms that synthesize useful products, e.g. hormones. It is also used to improve a feature of the recipient organisms, e.g. producing herbicide resistant in crop plants.Genetic engineering technologies aid the understanding of how organisms function by allowing scientists to study and alter gene function.Photo credit: Coneyl Jay / Science Photo Library
18 Recombinant technology Boardworks A2 BiologyGenetic TechnologiesOnce the gene for the desired protein has been identified, the following steps are carried out:1. Multiple copies of the desired gene are produced.2. The gene is inserted into a vector and transferred into host cells.3. The host cells that have successfully taken up the gene are identified using a marker.Teacher notesSee the ‘Studying Genomes’ presentation for more information about identifying genes.4. The host cells are allowed to multiply or are cloned.
19 Producing DNA copies from mRNA Boardworks A2 BiologyGenetic TechnologiesTeacher notesSee the Boardworks AS Biology ‘Infectious Diseases’ presentation for more information about how HIV uses reverse transcriptase to replicate its viral components in a host’s cell.
20 Producing DNA copies by cutting DNA Boardworks A2 BiologyGenetic TechnologiesTeacher notesRestriction endonucleases produced in bacteria are thought to have evolved as a defensive mechanism, to protect against invading viruses. The enzyme could cut the viruses’ genetic material into fragments preventing it from replicating. The host’s DNA is methylated by another enzyme in order to protect it from the activities of the restriction endonuclease.Certain sequences of DNA are the same whether they are read 5' to 3' or 3' to 5'. These sequences are called palindromic.
22 Bacterial conjugation Boardworks A2 BiologyGenetic TechnologiesMicroorganisms can naturally exchange genetic material in a process called conjugation. Genetic material in the form of plasmids can be copied and passed between bacteria.Some plasmids contain genes associated with antibiotic resistance. The movement of plasmids between individuals of the same and different species speeds up the spread of antibiotic resistance.Photo credit: Dr Linda Stannard, UCT / Science Photo LibraryTeacher notesSee the Boardworks AS Biology ‘Infectious Diseases’ presentation for more information about antibiotic resistance.
23 Boardworks A2 Biology Genetic Technologies Recombinant bacteriaBoardworks A2 BiologyGenetic TechnologiesTeacher notesThe uptake of plasmids by bacteria is aided by the presence of calcium ions in the medium and changes in temperature. These make the bacteria more permeable, allowing the plasmids to pass through the cell membrane. This is a very inefficient process - less than 1% of bacterial cells will take up a plasmid.
24 Boardworks A2 Biology Genetic Technologies Other genetic markersBoardworks A2 BiologyGenetic TechnologiesFluorescent markers and enzymes markers are also techniques to identify cells that have taken up the desired gene.A gene from a jellyfish that produces a protein called green fluorescent protein (GFP) can be used. The desired gene is transplanted into the centre of the GFP gene. The cells that have not taken up the desired gene will fluoresce.Using enzyme markers involves transplanting the desired gene into the centre of a gene coding for lactase. Lactase will turn a particular colourless substrate blue, therefore cells that have taken up the desired gene will not turn this substance blue.
25 Boardworks A2 Biology Genetic Technologies Viruses as vectorsBoardworks A2 BiologyGenetic TechnologiesViruses naturally transfer their genetic material into their host’s cells, as they need the host to produce viral proteins to allow them to replicate. Scientist use viruses, such as the adenovirus, as vectors in DNA technology.viral genomeThe genetic material that causes virulence must first be removed from the virus. The desired gene can be added to the viral genome.Teacher notesNon-biological vectors include:Ballistic impregnation – DNA coated with tungsten or gold particles is fired into plant cells. This has been used in the modification of several crop plants, including wheat.Electroporation – temporary pores are created in cells using bursts of electricity. These allow DNA to enter the cell.Micro-injection – DNA is injected into the nucleus using a very fine pipette.Liposome transfer – the DNA is coated by a liposome, which enables it to move through the cell membrane.The virus infects the target cells, inserting its genome so that the target cells then express the new sequence.adenovirus
26 Enzymes in genetic technology Boardworks A2 BiologyGenetic Technologies
27 Genetic engineering: true or false? Boardworks A2 BiologyGenetic Technologies
28 Boardworks A2 Biology Genetic Technologies Teacher notesIn ‘Slide Show’ mode, click the name of a section to jump straight to that slide.
31 Boardworks A2 Biology Genetic Technologies Golden RiceBoardworks A2 BiologyGenetic TechnologiesRice that has been engineered to contain beta-carotene is known as Golden RiceTM. Beta carotene is converted into vitamin A when digested.Golden Rice is thought to have potential benefits, as vitamin A deficiency currently affects a large number of people in economically less developed countries.Photo credit: Golden Rice Humanitarian Board (Teacher notesWhen the original strain of Golden Rice was released in 2000 there were concerns that it did not contain enough beta-carotene. It was thought that children would not be able to obtain the recommended daily requirement from eating normal quantities of the rice. However, in 2005 a new strain was released that contains 20 times as much beta-carotene as the original strain.There are also concerns that genetically-modified crops will be forced upon developing countries. Some people argue that malnutrition is caused by poverty and a lack of a balanced diet rather than vitamin deficiencies of a specific crop.